This application claims the priority of German Patent Application No. 201 02 048.3 filed Feb. 6, 2001, which is incorporated herein by reference.
The invention relates to a safety device for a steam-frothing device for producing a frothy beverage. More specifically, the present invention relates to a safety device of a steam-frothing machine or device for producing a frothy beverage, particularly frothy hot chocolate or cappuccino, which machine has a steam pipe that is connected to a steam generator and that has a steam discharge exit, and has a frothing head that encloses the steam discharge opening in the mounted state.
Typically, cappuccino is prepared with an espresso machine, with milk froth being produced in a separate milk container that is a component of the espresso machine and is connected to the machine""s steam generator. To produce cappuccino or frothed milk without a costly espresso machine, however, a relatively simple steam-frothing device can also be provided, the device essentially encompassing a steam generator and an automatic froth nozzle.
Analogously to an espresso machine, a steam-frothing device of this type includes a steam generator, which may be embodied as a flow heater, and a pump, which is connected to a water reservoir for pumping controlled amounts of water through the flow heater to create steam. When the steam-frothing device is turned on, a heating element of the flow heater is activated and maintained, by a thermostat at a predetermined temperature in a stand-by mode. To produce the steam, a steam start key is depressed, thereby activating the pump. This causes water to be pumped out of the reservoir and into the flow heater, where it evaporates and flows, as slightly over-stressed steam, through the frothing head adjoining the steam pipe. The frothing head is embodied such that a vacuum is generated inside it when the steam passes through, which vacuum simultaneously draws milk out of a separate milk container and air into the head. Inside the frothing head, the milk and air are whipped together. The milk froth exiting the frothing head can flow directly into a vessel positioned beneath the frothing head.
It is desirable to be able to remove the frothing head from the steam line, particularly because the frothing head contains dried milk residue following the froth preparation, and therefore must be washed. For this purpose, the head is embodied or formed to be easily removed from the steam pipe. If the steam start key is accidentally pressed when the frothing head is removed, over-stressed steam rapidly exits the steam discharge opening of the steam pipe, which may also be referred to as the steam discharge pipe, typically downward, so the operator faces the threat of being scalded.
Because the frothing device can be used not only to make cappuccino, a frothy coffee-and-milk beverage, but also frothy hot chocolate, a favorite children""s beverage, and it must be considered that children may wish to prepare the frothy hot chocolate themselves, it is an object of the present invention to make the steam-frothing device safer to handle.
Accordingly, it is an object of the present invention to configure a safety device for a steam-frothing device of the generic type mentioned at the outset such that, if an operator makes an operating error, such as activating the steam release when the frothing head is removed, the operator is reliably protected from steam exiting the steam pipe, without further complicating the operation.
The above object generally is accomplished according to the present invention in that a hollow body can be pushed onto the steam pipe, with the hollow body, permitting an essentially downward discharge of steam in an enabling position, and essentially blocking the downward steam discharge when in a position other than the enabling position of the hollow body. The hollow body that can be pushed onto the steam pipe is either a sliding sleeve that is pushed upward with the frothing head when the head is placed on the steam pipe, or, in a suitable embodiment of the steam pipe, is the frothing head itself. In both cases, a downward steam discharge that may injure an operator is effectively prevented when the frothing head is not connected to the steam pipe. It is not necessary to perform a separate operating procedure to prevent the undesired exit of steam.
In the first embodiment of the safety device, the hollow body is a sliding sleeve that is mounted on the steam pipe, and that is automatically pushed into a blocking position due to prestressing or biasing by a spring when the frothing head is removed from the steam pipe. In this blocking position, the hollow body prevents an undesired steam discharge from the steam discharge opening in a manner to be described below. When the frothing head is pushed onto the steam pipe, the frothing head pushes the sliding sleeve into an enabling position, in which it permits a discharge of steam from the steam discharge opening. The operator therefore need not take any further operating measures other than normal handling of the frothing head for activating the safety device and preventing a steam discharge in a dangerous direction.
According to one version of the first embodiment of the invention, the sliding sleeve is a component of a steam-frothing device having a circuit that activates the production and release of steam, usually a pump and a steam starting contact, that can be actuated by a steam start key. The safety device includes a movable blocking element that is actuated by the sliding sleeve and is formed such that it blocks the steam start key and/or the circuit in the blocking position. The safety device thus includes only a few additional parts, particularly the sliding sleeve and the blocking element.
In a preferred version of the safety device, the circuit that activates the steam release includes a pair of normally open contacts, with the starting contact being connected in series with a second contact. The two contacts can be activated or closed by the blocking element, and by the steam start key, respectively. The pump is only activated when the steam start key is depressed, which closes the steam starting contact of the contact pair, and the blocking element has closed the second contact of the contact pair in the unblocked or enabling position.
In accordance with another embodied of the safety device, the blocking element is a horizontally-pivotable double pivoting arm whose first arm is normally pivoted into a blocking position under the steam start key, where it prevents the key from being depressed, while the second arm cooperator with an inclined surfaces of a lifting arm that is connected to the sliding sleeve such that the first arm of the double pivoting arm is pivoted away from beneath the steam start key when the frothing head attached to the steam pipe raises the sliding sleeve. In this way, it is possible to lock and release a steam start key whose actuation direction extends parallel to the substantially vertical axis of the steam pipe to facilitate operation. The sliding sleeve is also displaced along this axis.
In this embodiment of the invention, the vertical sliding movement of the sliding sleeve is converted into a horizontal blocking movement of the double pivoting arm. For this purpose, the lifting arm has a lifting-arm angled or inclined member that engages an angled or inclined member of the second arm of the double pivoting arm. Moreover, the double pivoting arm is spring-loaded in the direction of the blocking position by a restoring spring. When the sliding sleeve with the attached lifting arm is raised, the angled member of the lifting arm presses the angled member of the second arm of the double pivoting arm to the side, so that the double pivoting arm is moved, counter to the force of the restoring spring, from the blocking position and into the enabling position. The sliding sleeve is spring-loaded such that the spring presses it downward. The displacement path of the sliding sleeve is limited by stop latches that are disposed on the sleeve, and that engage a housing bushing so that the sliding sleeve stops in the blocking position against the housing bushing. The blocking position is thus exactly defined.
A particular advantage in accordance with the sliding sleeve provided with the stops is that at least two vertical slots that are open at the top are cut into the sliding sleeve with mutual spacing at the circumference, so that a tab is respectively formed between the slots. For mounting the sliding sleeve, the tab or tabs can be resiliently compressed, so that the sleeve can easily be inserted into and through the housing bushing, after which the compressed tabs can re-expand and the stop latches slide outward past an upper edge of the housing bushing.
In a second variation of the safety device, the steam discharge opening of the steam pipe is essentially oriented radially toward the back of the steam-frothing device housing, i.e., in the direction of a front housing wall. The brewing head itself serves as the hollow body that can be pushed onto the steam pipe. The frothing head is internally configured so that follows: A vertical groove, which is open at the bottom, is cut into the upper region of the cylindrical or sleeve portion of the head to form a steam conduit, into which the steam discharge opening of the steam pipe terminates when the brewing head is pushed onto the steam pipe and is therefore operational. If, in contrast, the frothing head is removed from the steam pipe and the steam start key is inadvertently activated, the steam exiting the steam discharge opening of the steam pipe does not travel downward to hit the operator, but instead is directed away toward the front housing wall, where the steam cools, partially condenses and partially runs off harmlessly to the sides. The condensate can be collected in a collection tray. Preferably, the frothing head with the above-described internal configuration comprises two parts, i.e., a cylindrical sleeve portion containing the vertical grave and a frothing head portion and is therefore easier to clean and simple to manufacture.
Three exemplary embodiments of the safety device in accordance with the invention are described below, in conjunction with the five figures of the drawing, from which further features of the invention ensue.